package main

import (
	"fmt"
	"sort"
)

func main() {

	var s f

	s = []int64{1, 2, 3, 4, 5, 6}

	fmt.Println(sort.IsSorted(s))
	//true
}

type f []int64

func (f f) Len() int {
	return len(f)
}

func (f f) Less(i, j int) bool {
	return f[i] < f[j]
}

func (f f) Swap(i, j int) {
	f[i], f[j] = f[j], f[i]
}
